Control Strategies

A control strategy is a set of discrete and specific measures identified and implemented to achieve reductions in air pollution. These measures may vary by source type, such as stationary or mobile, as well as by the pollutant that is being targeted. The purpose of these measures is to achieve the air quality standard or goal. Costs and benefits are assessed in the development of the control strategy.

Control strategy development is the process of assessing specific abatement measures, management practices, or control technologies to determine the best combination of approaches to provide the emission reductions necessary to achieve the air quality standard or goal. Three primary considerations in designing an effective control strategy are:

(1) Environmental: factors such as equipment locations, ambient air quality conditions, adequate utilities (i.e., water for scrubbers), legal requirements, noise levels,
and the contribution of the control system as a pollutant;

(2) Engineering: factors such as contaminant characteristics (abrasiveness, toxicity, etc.), gas stream characteristics,
and performance characteristics of the control system; and

(3) Economic: factors such as capital cost, operating costs, equipment maintenance, and
the lifetime of the equipment. Air pollution officials should also consider pollution prevention which includes eliminating as much of the pollution emissions as possible at the source, substituting raw (and less toxic) materials,
considering alternative manufacturing processes, and improving process control measures.

Controls on major stationary, mobile, and area sources are part of a successful control strategy. These controls should utilize reasonably available control technology. Examples include controls on volatile organic compounds from solvent and paint usage as well as controls on nitrogen oxide emissions from combustion units. For mobile sources, examples include tighter emission controls for vehicles and low-sulfur fuel standards. For major stationary sources, it is beneficial to issue permits including emission limitations for any major sources, new and existing. The basic types of emission control technology are mechanical collectors, wet scrubbers, bag houses, electrostatic precipitators, combustion systems (thermal oxidizers),
condensers, absorbers, adsorbers, and biological degradation. The selection procedure should be based on the environmental, engineering, and economic considerations described above.

National or local governments new to the air quality management process should focus on obvious sources of air
pollution and the quickest means of control - more sophisticated and comprehensive strategies can be developed over time. Innovative strategies such as emissions trading, banking, and emissions caps can be incorporated as a further refinement
as the strategy continues. These strategies may be used in addition to the "command-and-control" type regulations which have traditionally been used by air pollution control agencies. Local and regional control measures and are both necessary for a successful strategy.

A control strategy developed by a local government may include locally appropriate measures, as well as control measures that the national government mandates be
implemented nation-wide. Successful control strategies are usually adopted into a regulatory program with implementation deadlines and mechanisms for enforcement. Different control measures may be mandated at different levels of government, from local to provincial, state level to national. In general, regulations established at the national level tend to have the most benefit while minimizing boundary and competition issues. The goal for all control strategies is to achieve real and measurable emission reductions.

(1) Determine priority pollutants. The pollutants
of concern for your location should be based on health effects and the
severity of the air quality problem.

(2) Identify control measures. For specific source categories,
choose the appropriate controls based on the priority pollutants identified.
A good source for control technologies is U.S.
EPA's Clean Air Technology Center. Also, the National Association of Clean Air
Agencies (NACAA) has developed several documents that
provide a menu of control options. To order any of these documents (listed
below), visit the NACAA
website.

Controlling Particulate Matter Under the Clean Air Act: A Menu of Options

Controlling Nitrogen Oxides Under the Clean Air Act: A Menu of Options

Meeting the VOC 15% Rate-of-Progress Requirement Under the Clean Air Act: A Menu of Options

Toxic Air Pollutants: State and Local Regulatory Strategies

(3) Incorporate the control measures into a plan. Using the control measures identified,
create a written plan with implementation dates to formalize the strategy. It is important to
adopt a regulatory program and include it in the plan so that control measures will be enforceable.

(4) Involve the public. As with the other management
activities related to the AQM process, it is critical to contact the regulated
community and other affected parties, as the
public should be consulted as part of the strategy development process.
This early consultation reduces later challenges and streamlines implementation.

In the U.S., individual states are responsible for this process and they
develop their own plan (called the State Implementation Plan, or SIP)
based on the air quality issues that are of concern in their region. The
SIP is the federally-enforceable plan that identifies how that state will
attain and/or maintain the primary and secondary National Ambient Air
Quality Standards (NAAQS) set forth in the Clean Air Act (CAA). Each state
is required to have a SIP which contains the control measures and strategies
developed through a public process and is formally adopted by the state
and submitted to the U.S. EPA. For several examples, see the local and
state implementation
plans created for states and counties within U.S. EPA's Region 4 (one
of ten EPA regions in the U.S.). These plans cover the control of all
air pollution issues from industry and automobile emissions to open burning
and more. Another example is given in the SIP
Plan Summaries for the New England region of the U.S.

For a case study on the development of ozone and particulate matter control
strategies in the U.S. state of California, see the control strategy chapter
in the air quality management plan for the South Coast Air Quality Management
District of California. This document
is available in English, Spanish, Chinese and Korean.